JP2006253207A - Method of coating, method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of coating which can suppress an inconvenience generating by rising of the coat. <P>SOLUTION: The method of coating includes the steps of forming the first coat on a semiconductor wafer, performing the edge rinsing of the first application film, performing a depletion treatment for the rise of the first coat formed in the case of edge rinsing, and performing the formation of the second coat on the first coat. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coating film forming method and a semiconductor device manufacturing method using the same.

  Along with the miniaturization of semiconductor devices in recent years, the exposure light source has been shortened in the photolithography technology, and at the same time, the lower layer of the photoresist film is used to suppress the influence on the line width variation due to reflection from the semiconductor wafer. Organic anti-reflective coating (BARC: Bottom Anti-Reflective Coating) is widely used.

  This organic antireflection film can be formed by, for example, a spin coating method. Such an organic antireflection film and the photoresist film formed thereon can be continuously formed using the same spin coat resist coating apparatus. For this reason, organic antireflection films are widely used in the field of semiconductors.

Here, the processing method of the to-be-processed film | membrane using the conventional organic antireflection film is demonstrated using FIGS. 7-11 (a), (b) (for example, refer patent document 1).
FIGS. 7 to 11 (a) and (b) are cross-sectional views each showing a peripheral portion of a semiconductor wafer, (a) is a cross-sectional view of a region where a resist film remains after development, and (b) FIG. 5 is a cross-sectional view of a region where no resist film remains after development. Accordingly, (a) and (b) are the same in the state before development (FIGS. 7 to 9).

First, a film to be processed 3 made of an insulating film, a conductive layer, or the like is formed on a semiconductor wafer 1, and an organic antireflection film 5 is formed thereon by a spin coating method, as shown in FIGS. 7 (a) and 7 (b). Get the structure shown.
Next, the rinse solution is dropped on the edge portion 1 a of the wafer 1 to perform the edge rinse of the organic antireflection film 5, and at the same time, the back rinse for removing the organic antireflection film 5 wrapping around the back surface of the wafer 1 is performed. The structure shown in FIGS. 8A and 8B is obtained. As shown in FIGS. 8A and 8B, when the above processing is performed, a bulge portion 7 is formed in the organic antireflection film 5 due to film shrinkage due to the influence of surface tension or the like.
Next, after the organic antireflection film 5 is baked, a photoresist film 9 is formed thereon by spin coating, and edge rinse is performed to obtain the structures shown in FIGS. 9A and 9B.
Next, the photoresist film 9 is patterned by exposure / development of the photoresist film 9 to obtain the structures shown in FIGS. As described above, FIG. 10A is a cross-sectional view of a region where the resist film remains after development, and FIG. 10B is a cross-sectional view of a region where the resist film does not remain after development. ), The photoresist film 9 is removed.
Next, the processed film 3 is etched using the patterned photoresist film 9 as a mask to obtain the structure shown in FIGS. 11A and 11B, and the processing of the processed film 3 is completed. .
JP 2001-217184 A

In this conventional method, as shown in FIG. 11 (b), the raised portion 7 of the organic antireflection film to be removed and the film to be processed 3 partially remain, and it peels off to generate particles. This has caused a decrease in manufacturing yield.
Further, as shown in FIG. 11A, the organic antireflection film 3 may not be present below the edge portion 9a of the photoresist film 9, which may cause a processing failure of the film 3 to be processed. It was. If the number of shots on the edge portion 9a is reduced, the above processing defects can be avoided. In this case, however, the number of chips is reduced.

  This invention is made | formed in view of the situation which concerns, and provides the coating film formation method which can suppress the problem which arises due to the swelling part of a coating film.

Means for Solving the Problems and Effects of the Invention

In the coating film forming method of the present invention, a first coating film is formed on a semiconductor wafer, edge rinsing of the first coating film is performed, and the height of the raised portion of the first coating film formed at the time of edge rinsing is set. The process of performing the process to reduce and forming the 2nd coating film on a 1st coating film is provided.
According to the present invention, since the process of reducing the height of the raised portion of the first coating film is performed, inconvenience caused by the raised portion of the first coating film can be suppressed.

(Coating film forming method)
In the coating film forming method of the present invention, a first coating film is formed on a semiconductor wafer, edge rinsing of the first coating film is performed, and the height of the raised portion of the first coating film formed at the time of edge rinsing is set. The process of performing the process to reduce and forming the 2nd coating film on a 1st coating film is provided.

A semiconductor wafer consists of various semiconductors used for manufacture of semiconductor devices, such as Si and GaAs.
The first coating film is an organic antireflection film, for example, and can be formed by, for example, a spin coating method. The first coating film is usually formed through various processed films such as an insulating film and a conductive film formed on a semiconductor wafer.
Edge rinsing of the first coating film can be performed by dropping a rinsing liquid onto a portion near the edge of the wafer. The rinse liquid is composed of a liquid that can dissolve the first coating film, and the composition thereof is appropriately selected according to the material of the first coating film.

  Edge rinsing of the first coating film is performed while rotating the wafer, and the process of reducing the height of the raised portion consists of rotating the wafer at a higher rotational speed than the rotational speed during edge rinsing. Is preferred. By rotating the wafer in this way at high speed, the rinsing liquid in the raised portion is shaken off, and the raised portion is extended by centrifugal force, thereby reducing the height of the raised portion. The number of rotations of the wafer during the process of reducing the height of the raised portion is preferably 2 to 3 times higher than the number of rotations during edge rinsing. The effect of high-speed rotation is effectively obtained by setting the rotational speed higher than 2 times, and the coating film due to the influence of rebound of the rinse liquid from the spin cup and the occurrence of mist by setting the rotational speed lower than 3 times. Generation of defects is suppressed.

  The process of reducing the height of the raised portion may consist of pre-baking the first coating film and then selectively dropping a rinse liquid onto the rising portion of the first coating film. After the first coating film is lightly hardened by pre-baking, a rinsing liquid is selectively dropped onto the swelled portion, so that the swelled portion is dissolved in the rinsing liquid and its height is reduced.

  The second coating film is made of, for example, a photoresist film, and can be formed by, for example, a spin coating method. It is preferable that the second coating film is formed so that the edge thereof is located inside the edge of the first coating film. In this case, it is ensured that the first coating film always exists immediately below the second coating film. As a specific method, the width of the edge rinse when forming the second coating film may be made larger than that when forming the first coating film. In another method, when the second coating film is made of a photoresist film, the edge position of the second coating film may be adjusted by edge exposure.

(Method for manufacturing semiconductor device)
In the method of manufacturing a semiconductor device of the present invention, a film to be processed and an organic antireflection film are sequentially formed on a semiconductor wafer, edge rinsing of the organic antireflection film is performed, and an organic antireflection film formed at the time of edge rinsing is formed. A process of reducing the height of the raised portion, forming a photoresist film on the organic antireflection film, patterning the photoresist film, and etching the film to be processed using the patterned photoresist film as a mask. Prepare.

  The “organic antireflection film” and “photoresist film” in this production method correspond to the first coating film and the second coating film in the coating film forming method, respectively. Further, the description of the common part between the present manufacturing method and the coating film forming method is omitted.

  The film to be processed is a film processed by etching, and is made of an insulating film or a conductive film. This manufacturing method is used, for example, when a hole or a groove is formed in an insulating film, or when a conductive film is processed to form a gate electrode.

  In the conventional method, a portion of the film to be removed may remain when the film to be processed is etched due to the bulge portion of the organic antireflection film. Since the process of reducing the height of the raised portion of the prevention film is performed, the film to be processed that should be removed can be reliably removed.

  Hereinafter, an embodiment in which the present invention is applied to a gate electrode forming process will be described with reference to FIGS.

  FIGS. 1-6 (a) and (b) are cross-sectional views each showing a peripheral portion of a semiconductor wafer, (a) is a cross-sectional view of a region where a resist film remains after development, and (b) FIG. 5 is a cross-sectional view of a region where no resist film remains after development. Therefore, in the state before development (FIGS. 1 to 4), (a) and (b) are the same figure.

  First, a film to be processed 3 made of a polysilicon film having a thickness of 150 nm is formed on the semiconductor wafer 1 via a gate oxide film having a thickness of 3 nm. Next, the organic antireflection film 5 is formed on the obtained wafer by spin coating to obtain the structure shown in FIGS.

  The coating apparatus used here may be any coating apparatus that can use a commercially available spin coater having a plurality of hot plates. Further, after spin coating, a rinse solution is dropped on the outer periphery of the wafer while rotating the wafer. A device having a nozzle for removing a part (edge rinse) is preferable. Desirably, an apparatus in which the nozzle is movable and the width for removing the coating film can be arbitrarily set is suitable. An example is a Mark7 coater manufactured by Tokyo Electron.

  Specifically, for example, after the wafer 1 is adsorbed to a spin chuck, the organic antireflection film 5 solution of about 2 to 4 cc is applied to the center of the wafer 1 while rotating the wafer 1 at 200 to 1000 rpm. Dripping. Subsequently, for example, it is rotated at 1000 to 6000 rpm for about 15 to 20 seconds. By changing the number of rotations at this time, it is possible to control the film thickness of the obtained organic antireflection film 5 to a desired thickness. As the organic antireflection coating 5 solution, for example, DUV32 manufactured by Nissan Chemical Co., Ltd. is used.

  Next, the rinsing liquid is dropped on the edge portion of the wafer 1 to perform edge rinsing of the organic antireflection film 5. Specifically, using a rinse solution containing a propylene glycol monomethyl ether / propylene glycol monomethyl ether acetate solution such as OK73 thinner made by Tokyo Ohka Kogyo, the rotation speed is fixed at 2000 rpm, and the edge rinse is performed with a width of 1.5 mm from the wafer edge. I do. At the same time, a back rinse is performed to remove the organic antireflection film 5 that has gone around the back surface of the wafer 1. As a result, the structure shown in FIGS. 2A and 2B is obtained. The height of the raised portion 7 of the organic antireflection film 5 formed by the edge rinsing process is maximum in the wafer center direction by about 20 μm from the edge boundary of the organic antireflection film 5, and as shown in FIG. 7), the film thickness on the inner side of 7 may be 5 times or more.

  Thereafter, the wafer 1 is rotated for 60 seconds at a rotational speed of 5000 to 6000 rpm, and the rinse liquid is shaken off. In this step, the solution of the organic antireflection film 5 is volatilized, and at the same time, the raised portion 7 of the organic antireflection film is stretched by the centrifugal force at high speed rotation, and the height of the raised portion 7 is shown in FIG. As shown, it is suppressed to about 1.5 times the normal part.

  Next, the organic antireflection film 5 is cured by baking at 200 ° C. for 60 seconds using a hot plate. For example, the coating thickness of the organic antireflection coating 5 after baking is such that when the height of the normal portion is 60 nm, the height of the raised portion 7 is 90 nm.

  As another method for reducing the height of the raised portion 7, an organic antireflection film 5 is formed on the wafer 1, edge rinsing is performed, and then lightly cured by baking at 120 ° C. for 60 seconds on a hot plate. After that, there is a method of reducing the film thickness at the edge portion of the organic antireflection film 5 by dropping the rinse liquid again on the raised portion 7.

  Table 1 shows the film thickness measurement results obtained in this example and the conventional coating film forming method. The height of the raised portion 7 of the organic antireflection coating 5 is suppressed to about twice or less that of the normal portion, and good results are obtained. Have gained.

  Next, a photoresist film 9 is formed on the organic antireflection film 5 by spin coating. The coating apparatus and the coating method can be the same as those in which the organic antireflection film 5 described above is formed. Specifically, for example, the coating is performed with a thickness of 700 nm using PEK106A6 manufactured by Sumitomo Chemical. Subsequently, the photoresist film 9 is removed with a rinsing liquid at a width of 2 mm from the wafer edge, and the structure shown in FIGS. 4A and 4B is obtained. In this embodiment, the removal width (2 mm) of the photoresist film 9 is larger than the removal width (1.5 mm) of the organic antireflection film 5. Therefore, as shown in FIGS. 4A and 4B, the organic antireflection film 5 always exists in the lower layer of the photoresist film 9 to prevent defective pattern formation at the time of development or in a later process. can do.

  At this time, a raised portion is formed at the edge portion of the photoresist film 9 (not shown) in the same manner as the organic antireflection film 5 described above, but the raised portion of the photoresist film 9 is removed by edge exposure and development described later. Will not be a problem. Next, pre-baking is performed on a hot plate at a temperature of 100 ° C. for 60 seconds.

  Next, the photoresist pattern 9 is patterned into a desired pattern by performing circuit pattern exposure and edge exposure at 110 ° C. for about 60 seconds, followed by baking and development, and FIGS. 5A and 5B. The structure shown in is obtained. As described above, FIG. 5A is a cross-sectional view of a region where the resist film remains after development, and FIG. 5B is a cross-sectional view of a region where the resist film does not remain after development. Only in (b), the photoresist film 9 is removed.

Here, the organic antireflection film 5 is always present in the lower layer of the photoresist film 9 even when a shot region is present on the edge of the wafer at the time of exposure. Can be prevented. For this reason, it is not necessary to reduce the shot of the portion on the wafer edge, so that the maximum number of chips that can be formed on the wafer 1 can be ensured.
Although the edge removal width of the photoresist film 9 is adjusted by edge rinsing in this embodiment, it is not limited to this and may be adjusted before development. For example, the edge rinse width is set to be small (for example, 1 mm), and the edge position of the photoresist film 9 is adjusted in the wafer center direction with respect to the edge position of the organic antireflection film 5 during edge exposure. May be.

Next, the organic antireflection film 5 is removed by dry etching using the photoresist film 9 as a mask. Specifically, for example, using a mixed gas of Cl ₂ and O ₂ , dry etching of the organic antireflection film 5 is performed with an etching amount about twice the coating film thickness. By performing under these conditions, the organic antireflection film 5 to be removed can be reliably removed even at the raised portion 7 of the organic antireflection film 5. Thereafter, the film to be processed 3 is etched using, for example, a mixed gas of Cl ₂ , HBr, and O ₂ to form a gate electrode as shown in FIGS. 6 (a) and 6 (b).

It is sectional drawing which shows the gate electrode formation process of the Example of this invention. It is sectional drawing which shows the gate electrode formation process of the Example of this invention. It is sectional drawing which shows the gate electrode formation process of the Example of this invention. It is sectional drawing which shows the gate electrode formation process of the Example of this invention. It is sectional drawing which shows the gate electrode formation process of the Example of this invention. It is sectional drawing which shows the gate electrode formation process of the Example of this invention. It is sectional drawing which shows the process process of the to-be-processed film of a prior art example. It is sectional drawing which shows the process process of the to-be-processed film of a prior art example. It is sectional drawing which shows the process process of the to-be-processed film of a prior art example. It is sectional drawing which shows the process process of the to-be-processed film of a prior art example. It is sectional drawing which shows the process process of the to-be-processed film of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor wafer 3 ... Processed film 5 ... Organic anti-reflective film 7 ... Swelling part 9 of organic anti-reflective film ... Photoresist film

Claims (13)

The first coating film is formed on the semiconductor wafer, the first coating film is edge-rinsed, and the first coating film is processed to reduce the height of the raised portion of the first coating film formed during the edge rinsing. A coating film forming method comprising a step of forming a second coating film on a film. Edge rinse of the first coating film is performed while rotating the wafer,
The method according to claim 1, wherein the process of reducing the height of the raised portion includes rotating the wafer at a higher rotational speed than the rotational speed during edge rinsing. The method according to claim 2, wherein the number of rotations in the process of reducing the height of the raised portion is two to three times higher than the number of rotations in edge rinsing. The method according to claim 1, wherein the process of reducing the height of the raised portion includes pre-baking the first coating film, and then selectively dropping a rinse solution onto the raised portion of the first coating film. . The method according to claim 1, wherein the second coating film is formed so that an edge thereof is located inside an edge of the first coating film. The method according to claim 1, wherein the first coating film is made of an organic antireflection film, and the second coating film is made of a photoresist film. The method according to claim 1, wherein the first and second coating films are formed by a spin coating method. A processing film and an organic antireflection film are sequentially formed on a semiconductor wafer, edge rinsing of the organic antireflection film is performed, and the height of the raised portion of the organic antireflection film formed during the edge rinse is reduced. A method of manufacturing a semiconductor device, comprising: performing a step of forming a photoresist film on an organic antireflection film, patterning the photoresist film, and etching the film to be processed using the patterned photoresist film as a mask. Edge rinsing of the organic antireflection film is performed while rotating the wafer,
9. The method according to claim 8, wherein the process of reducing the height of the raised portion comprises rotating the wafer at a higher rotational speed than the rotational speed during edge rinsing. The method according to claim 9, wherein the number of rotations during the process of reducing the height of the raised portion is two to three times higher than the number of rotations during edge rinsing. The method according to claim 8, wherein the process of reducing the height of the raised portion includes pre-baking the organic antireflection film, and then selectively dropping a rinse solution onto the raised portion of the organic antireflection film. . The method according to claim 8, wherein the photoresist film is formed such that an edge thereof is located inside an edge of the organic antireflection film. The method according to claim 8, wherein the organic antireflection film and the organic antireflection film are formed by a spin coating method.

Images